Detonator



c; A. HOUCK ET AL A ril as, 1959 DETONATOR Filed Dec. 18, 1953 2Sheets-Sheet 1 INVENTORS United S ates Patent i DETONATOR ApplicationDecember 18, 1953, Serial No. 399,032

4- Claims. (Cl. 102-20) This invention relates to apparatus employed inperforating well casings by explosive means, and more particularly to anovel means for detonating a detonable fuse of the type employed todetonate one or more explosive units which in turn, when detonated,perform a function in casing perforation.

It is customary, in perforating well casings in situ to employ one orthe other of two principal perforating modes, the first of whichinvolves firing hard projectiles through the casing and into thesurrounding cement and rock, and the second of which utilizes the uniquepiercing characteristics of so-called shaped charges of high explosivematerial. A variety of means are employed in both modes for detonatingor firing the charges that propel the projectiles, or that by a sort ofjet-like action pierce an obstacle. One common means of thus firing ordetonating the charges is a length of relatively insensitive detonablefuse. The fuse may extend to one or more explosive units, and whendetonated serves in turn to fire or detonate substantiallysimultaneously or in rapid succession the several charges to which itextends. Fuse employed for this purpose is, due to the environment ofits use and for general reasons of safety to personnel and equipment,chosen from a variety of types, all of which are insensitive toordinary, severe handling shocks of both mechanical and thermal nature;and for that reason must be detonated by an extremely severe concussiveshock. Heretofore detonation of such fuse material has usually beeneffected by conventional electrical blasting caps containing a detonablematerial such as fulminate of mercury. It is well known that caps of thetype mentioned are apt to be accidentally detonated by relatively lightshock and are susceptible to detonation by static electricity, abrasionwith hard materials such as are employed for holding the cap, withtools, and with other caps; and that, therefore, considerable care mustbe exercised in handling such caps. As a consequence of the dangerinvolved in assembling apparatus of the nature of that hereinbeforementioned and employing blasting caps as a fuse detonating means, fieldassembly and field renewal of the apparatus has been precluded, and suchoperations have been carried out in specially prepared places and onlyby skilled personnel.

The present invention provides means for detonating fuses of the typeaforementioned without use of blasting caps or any other means ormaterials sensitive to ordinary handling shock, whereby assembly of thefuse and apparatus in its container or supports may be safely effectedwithout undue care in regard to the explosives employed. Additionallythe invention provides an apparatus for per forating well casings thatis readily and quickly and safely assemblable by ordinary workmen, andwhich is such that those expendable items of the apparatus that aredestroyed or consumed in the casing-perforating operation are easilyrenewed withan extreme measure of safety for adjacent personnel andequipment, permitting repersonnel. I

, 2,883,931 Patented Apr. '28, 1.9.59

ace.

Generally, the invention provides a novel detonator means which may beused in a string of interconnected perforating unit sectionsinterconnected at easily assembled and disassambled joints includingshort substitute joints or subs," the detonator means using the sectionsand subs as support means and employing an electrically ignited chargeof defiagrable material or powder not sensitive to ordinary handlingshock, to create pressure to disrupt or shear apart a piece of hardmaterial and propel, preferably, a portion or piece or fragment of thelatter along a preferably restricted path into detonating impingementwith a portion, preferably an end, of a detonable fuse held andpositioned in the path by a part of the means, whereby the fuse isdetonated without use of any means sensitive to ordinary handling shock.The means for detonating the fuse are preferably but not necessarilyformed as a principal bored and chambered plug snugly fitting in an endof a sub, into the chamber of which plug an electrically heated igniteris removably fitted, the chamber containing adjacent the igniter adefiagrable charge which in turn is restrained from exit from thechamber by a disruptable element, preferably in the form of a sheardisc, which serves to tightly close the chamber, the shear disc beingtightly held in posiiton by a bored member, readily yet tightly fittingin the bore of the plug as by being threaded thereinto, the bore of themember being completely covered at one end by the shear disc andpreferably being arranged to provide a restricted path for a projectileformed of a fragment of the shear disc upon disruption of the latter bypressure created by defiagration of the deflagrable charge; the meansalso including a fuse holding and positioning device arranged to holdand position a portion, preferably an end, of a detonable fuse either inthe bore of the member or outside but in axial alignment therewith, sothat the fragment of the shear disc will, with a high degree ofcertainty, be propelled at high speed into detonating impingement orimpact with the fuse and detonate the latter. The plug is preferably ofa shoulderedcylinder form adapted to easily but snugly slide intoposition in one end of a sub with the shoulder abutting the end of thesub, and the bored member providing the restricted path for a fragmentof the disc preferably such as to screw readily but tightly into theinternally threaded bore of the plug to thereby tightly press the discin place over the powder chamber of the plug; and the fuse holding meansis preferably in the form of a readily removable means including a pinarranged transversely across the axis of the perforator sections, with ahole in the pin arranged in substantially axial alignment with the boreof the plug and member so that a portion, preferably an end, of adetonable fuse, either with or without an auxiliary charge, can bepositioned either in the bore of the member or outside but insubstantially axial alignment with said bore and in the direct path ofthe propelled fragment. The pin, the fuse, the shear disc, thedeflagrable charge, and the igniter may all be expendable items of theapparatus, are all quite readily assembled and replaced or renewed, andare, with all other parts of the apparatus, very insensitive to ordinaryhandling shocks.

With the aforementioned and other obvious disadvantages and dangers ofthe prior art devices and apparatus in view, it is accordingly, aprincipal object of the present invention to provide a detonator for adetonable fuse which is effective to detonate such a fuse without meansor materials sensitive to ordinary handling shock.

A further object of the invention is the provision of a readily andsafely renewable detonator for a detonable fuse, the detonator beingsimple in construction and highly effective to detonate the fuse in thecomplete absence of means sensitive to ordinary handling shock.

An additional object of the invention is the provision of a fusedetonator comprising a disruptable element, shock insensitive means todisrupt the element and propel at least a portion of the element along apath, and means to hold a detonable fuse with a portion thereof in thepath so the propelled portion of the element will make detonatingimpingement with the portion 'of the fuse disposed in its path.

Another object of the invention is to provide in a well casingperforator apparatus using explosive charges in the perforatingoperation and a detonable fuses to detonate the charges, a simple andsafe detonator for detonating the fuse, the apparatus including thedetonator comprising only parts and materials not sensitive to ordi- 4frusto-conical end of a charge-aligner 21 forming part of anexplosive-containing shaped-charge unit 22, or a means hereinafterdescribed in detail. Diametrically opposite each aperture 18 is arespective recess 23 formed in the interior wall of the perforatorsection, and the recess being adapted to alternatively receive a pin,hereinafter described, or the cylindrical base 24 of a shapedcharge unit22. Units 22 are of conventional commercial form and may be such as aredisclosed in the application for patent of Lindsay et 211., Serial No.106,567, filed July 25, 1949, now US. Patent No. 2,707,917, issued May10, 1955.

A length of detonable fuse 25 such as Primacord 5O grain 'PETN,manufactured by Ensign-Bickford Company, for example, is arranged ineach perforator section 12 for detonating the shaped charge units 22 inthe reponents of the invention and indicating the general relathereindicated by the bracketed portion A, and showing certain detailspertinent to the subject matter of the invention; A

Fig. 2B is a longitudinal sectional view similar to Fig. 2A and showingdetails of structure included in that bracketed at B in Fig. 1;

Fig. 3A is a fragmentary detail view on a plane indicated by line 3-3 ofFig. 2B, principally in section, and illustrating the means for holdingand positioning a portion of one kind of detonable fuse in the path of apropelled fragment; and

Fig. 3B is a view similar to Fig. 3A but depicting the holding meanspositioning another kind of detonable fuse in the path of a propelledfragment.

' -Referring to 'the drawings, and to Fig. 1 thereof in particular, awell casing perforating apparatus assembly is indicated generally byordinal 10, the apparatus comprising an upper cylindrical body section11, a series of interconnected perforator sections indicated generallyat 12, the lowermost one of which is terminated by a bull plug 13. Whilebut two sections 12 are shown, it will be understood that only one suchsection may be employed, or two or more, as conditions and requirementsof the perforating operation dictate. Each of sections 12 above thelowermost thereof includes a substitute joint or sub 14 at its lowerend, the bull plug 13 serving in lieu of a sub for the lowermost of thesections. The upper part of body section 11 is provided with anupstanding cable head 15 in which is secured and sealed in conventionalmanner a suspending cable 16 which comprises an insulated electricalconductor 17 whose purpose is to supply the suspended apparatus withelectric current, the grounded exterior of the metallic body of theapparatus and the earth serving as a return path for the current.

Each perforator section 12 is provided with a plurality .of threadedapertures 18 (see Fig. 2A), each equipped spective section, the fuseextending through holes formed in the bases 24 of units 22, one hole 'toeach of the units, and extending downwardly below the lowermost unit 22in the section. This downwardly extending end portion 26 of fuse 25 ispreferably but not necessarily encased in a stifi tubular case 27 (seeFig. 3A) formed of fiber or other stiff material, or may be providedwith a closedend case 27a (see Fig. 3B), formed of fiber or metal andpartly filled with detonable material28 of the same composition as thatemployed in fuse 25, selection of the type of case depending upon therelative insensitivity to shock of the type of detonable fuse employed.For types of fuses extremely difficult to detonate, and with otherconsiderations set out hereinafter in mind, the.closedend case ispreferred; whereas for other types of detonable fuses a tubular case, ascase 27, or no case at all, is sufficient. Detonable material 28, beingof the same type or composition as that employed in fuse 25, is notsensitive to ordinary handling shocks, hence either arrangement of fuseend may readily be assembled in the apparatus of the invention byunskilled personnel with out danger of accidental detonation.

A portion of the fuse, such as end 26, is held in position fordetonation by means including a pin 30 suitably shaped as indicated frommetal, thermo-setting resin or other suitable material, the pin beingformed at one end to snugly fit in one of the recesses 23 and at itsother end with an exterior taper complementary to the taper of a plug 19and further with an internal bore 31 arranged to'receive a compressionspring 32 adapted to be compressed by plug 19 when the latter is screwedhome in recess 18. Pin 30 is provided with a transverse hole or bore 33through which the end 26 of the fuse 25 is threaded, the fuse being heldtherein by suitable means such as the force of gravity, a friction fit,wedge means, or, preferably and as illustrated, by an elastic grommet 34applied over the end of the fuse and forced into position along the fuseand into contact with pin 30. A suitable length of the fuse is leftprotruding from the lower side or face of the grommet, as willhereinafter be explained in more detail.

Situated below each pin 30, and supported by the sub 14 (or bull nose13) secured to the lower end of a section 12 is a detonator indicatedgenerally in Fig. 1 by ordinal 36 and comprising a chamber-forming meanspreferably in the form of a bored plug 36a (Fig. 2B) dimensioned to fitsnugly in the upper cylindrical part of the respective sub 14 or nose13, as indicated. Plug 36a is preferably formed with an internallythreaded bore 37, a smaller step-bore 38 and a still smaller andpreferably slightly tapered chamber-forming bore 39 having a generallyconical base 40 terminating in an igniter-pin receiving aperture or bore41, which in turn is provided with a flared lower opening 42. Plug 36aalso is provided with a circumferentially disposed series oflongitudinally extending bores 43, two of which are shown in Fig. 2B,each positioned close to the outside of the plug as indicated andserving to pass electric conductors Also comprised in the detonator 36is a means in the form of a preferably bored plug member 44 formed to bemounted tightly and securely in bore 37, as by means of complementarythreads as illustrated, for example; the plug having a preferablystraight bore or passage 45 so dimensioned and positioned that when plug44 is tightly engaged with the bottom of bore 37, bore or passage 45 isin substantially axial alignment with both hole 33 of pin 30 andchamber-forming bore 39 of plug 36a, and such that the diameter orprincipal dimension of bore or passage 45 is somewhat less than that ofbore 38 and of bore 39. Bore or passage 45 is preferably terminated atits upper or outer end by a conical recess 46 which is adapted to guideand receive the end 26 of a fuse 25 when the apparatus is assembled.Also, the length of the straight part of bore 45 is preferably of theorder of one inch, although considerable variation in this dimension ispermissible, depending upon other design factors. 7 V

Tightly pressed into place in short step-bore 38 by plug member 44 is apreferably recessed disruptable element 47 preferably of the characterof a shear-disc of mild cold-rolled steel or similar material. Element47 retains in place in slightly tapered bore 39 a cylinder 49 of fiberor similar suitable material, which rests on the conical base 40 and inturn serves to aid in sealing in bore 39 a deflagrable charge 50 of acommon propellant powder and an electrically operable igniter 51 havingan electrically insulated pin 52 extending through a conical sealingplug 53 and insulating washer 54 as indicated, the pin being threaded atits end to receive suitable nuts 55 to secure the igniter in positionand to receive a suitable electric conductor as will hereinafter be exlained. Charge 50 is insensitive to ordinary handling shock and may, byway of example, be a pellet containing 30 grains of Hercules H.E.S.5002.180 propellant powder; and igniter 51 may be of a type using afusible electric filament embedded in black powder, or such as is fullydisclosed in the patent to Phillips, No. 2,649,736 issued August 25,1953. The arrangement and proportions of the structures just describedare such that when electric current is supplied to igniter pin 52 andreturned through the interconnected metallic bodies of the severalstructures to the source, deflagrable charge 50 is ignited ordefiagrated and produces a high pressure in the chamber formed by bore39. As this pressure increases to near its peak value, a fragment orportion of disruptable element 47 is broken or sheared out, usually inthe form of a round slug or fragment, the latter is propelled at highspeed along a more or less confined path provided in bore or passage 45,and into detonating impingement with that portion of fuse 25 which isdisposed in its path. While bore or passage 45 is illustrated as acylindrical bore since that shape is perhaps easiest and simplest toform, the passage could well be of other shape, and could be ofdimensions different from those of the end portion of fuse 25. Also,while element 47 has been illustrated as a simply coined disc, it could:be of frangible material of other type and shape, it being necessaryfor the purposes of the invention only that the pressure provided inchamber or bore 39 be sufiicient to disrupt and propel a portion, eitherall or a part, of element 47 into detonating impingement with or upon aportion of fuse 25. Further, while for the sake of simplicity and easeof assembly the end face of the fuse, in the disclosed embodiment of theapparatus, forms a target for the propelled portion of element 47, it isevident that a loop of fuse 25 could also be used at the target. Thus,for example, the chamber could be of spherical shape with the fusearrayed on the interior wall with a disruptable element in the form of afrangible sphere inside and containing the igniter at its centersurrounded by the defiagrable charge, whereby at least one portion ofthe frangible sphere would be propelled into detonating impingement withthe detonable fuse.

Plug 36a is formed with means to hold it in position against unduedownward descent in the bore of a sub or nose 13, the means preferablybeing in the form of an annular shoulder resting on the end of the subor nose, as indicated; and the plug is held from upward dislodgement inthe assembled apparatus by a transversely notched internally-threadedsleeve 36b which is attached to the upper end of plug 36a as by means ofa threaded joint as illustrated, the sleeve having opposed holdingnotches 36c complementary to pin 30 as indicated in Fig 23.

Referring now to Fig. 2A, body section 11 is provided with a bore 56having internal threads for a threaded joint 57, and an internal uppershoulder 58 An adapter plug 59, provided with an external upwardlyfacing shoulder 60 and a threaded upper central periphery is screwedinto the lower end of bore 56. This plug is provided with acircumferentially arranged series of longitudinally extendingthrough-holes 61 for reception of a plurality of connector bolts such as62, 62a, which latter are each encircled by a respective tubularinsulator sleeve 63 and a pair of end insulating washers 64, 64, theinsulator devices serving the obvious function of electrically isolatingthe through-bolts from the metal of adapter plug 59. Nuts, as shown, areprovided to retain the bolts in place.

Positioned in bore 56 immediately above the connector bolts and plug 59is a terminal block 65 having sockets in its lower end and makingcontact with respective connector bolts, and having conductors such as65b, 65c, one for each socket, leading upwardly through the block, thelatter being properly oriented in bore 56 with respect to the severalbolts by any suitable means, as, for example, a pin 66 mounted in plug59' and engaging in a complementary hole in the terminal block.Positioned above terminal block 65 in body section 11 is a circuitcontroller 65a (see Fig. 1) which may be of any suitable type and, forexample, may be like or similar to that fully described in the patent toJohnston, No. 2,048,451. The purpose of controller 65a, to which theconductors such as 65b, 65c lead, is to provide electric current to eachof the conductors in a prearranged sequence, as is explained in thepatent.

The connector bolts such as 62, 62a, have secured to their lower ends,as by soldering, respective insulated conductors such as 67, 68 whichare provided in excess length and which extend loosely downwardly past22 and through one or another of bores 43 in plug 36a, from which oneconductor, such as 67, extends to and terminates at, an igniter pin 52as shown in Fig. 2B. Others of the conductors, such as 68, extenddownwardly and are secured to respective ones of connector bolts such as6211, similar to bolts 62, 62a. Connector bolts such as 62b are arrangedin an adapter plug 69 which in all material respects may be similar toplug 59 and which is secured in place in similar fashion, in the lowerend of the bore of sub 14. Conductors such as 70 are secured torespective connector bolts such as 62b and extend downwardly therefromto other of igniter pins such as 52, there being an igniter pin in adetonator for each of the peiforator unit sections such as 12. Conductor70 may, for example, lead to the lowermost detonator 36, which islocated in the upper end of bull nose 13 and the lower end of thelowermost perforator section 12, as indicated in Fig. 1.

As employed herein, the term deflagrable charge is intended to denote acharge of combustible material capable when ignited of burning rapidlyor deflagrating with release of. considerable energy, but yetinsensitive to ordinary handling shock. Typical of such charge is acharge of Hercules H.E.S. 5002.180 powder; and in contrast thereto is acharge of fulminate of mercury, which is normally a detonable substancesensitive to ordinary thermal and mechanical shocks such as slightabrasion, and which violently explodes when ignited or subjected tomechanical shock. By detonating is usually meant combustion at such arapid rate that a sudden and violent explosion results. By theexpression ordi.

nary handling shock is meant that type of shock, whether thermal ormechanical or of other nature, to which the Combustible or detonablematerials or devices of the nature of those disclosed are in any waylikely to be subjected in normal handling, assembly, and usageprocedures and that type of shock being of such characteristics thatsubjection thereto of such sensitive devices as blasting caps would atleast occasionally result in ex plosion of the sensitive device.Further, as employed herein, the term detonating impingement is intendedto mean the engagement of a moving body or element with a detonablematerial with such speed and energy of impact that the detonablematerial detonates. By the expression sensitive to ordinary handlingshock is meant lsuch sensitivity to thermal or mechanical shock orstatic electricity that explosion of the substance is likely to at leastoccasionally occur when the material or portions thereof are subjectedto such shocks as could normally be encountered in ordinary handling ofthe material, such as occur, for example, in handling, assembling,dropping, and the like.

While wide variations in design, loading, and assembly of'apparatusaccording to the invention are possible, one commercially acceptabledesign will be characterized as an example. Using the aforementionedPrimacord 50 'grain PETN fuse, the end being arranged as shown in Fig.2B of the drawings and spaced one and one-sixteenth inches from thenearest face of a shear disc or element '47 of mild cold-rolled steelone-tenth inch thick at the bore, a bore 45 of seven thirty-seconds ofan inch in diameter, a propellant charge loading density of 260 grainsper cubic inch of free space in chamber or bore 39 (26 grains in achamber free space of approximately one-tenth cubic inch volume), thepropellant being Hercules H.E.S. 5002.180, and plug member 44 and plug36a being of hardened steel, commercially acceptable detonation of thefuse is effected upon ignition of deflagrable charge 50 by igniter 51.

Several possible modes of assembly of the illustrated apparatus areapparent. With respect to the detonator proper, a cylinder 49 and anigniter are dropped into the chamber of plug 36a, seal plug 53, washer54 and a 'nut 55 applied and tightened, a defiagrable charge 50 'droppedin the chamber and an element 47 set in place pin 52 with a nut 55, plug36a dropped into sub 14 and the latter screwed onto section 12 (theexcess of wire such as 67, 68 permitting any necessary or accidentaltwisting); wires such as 68 then being secured to bolts such as 62b,plug 69 screwed into sub 14 (with excess wire again permittingtwisting), and the procedure con tinued until the perforator string iscompleted. Wires and electric conductors are preferably suitably codedto facilitate termination of the correct wire at each igniter .pin.Disassembly is obvious and is simpler and easier due to thedestructionin use of the expendable items such as igniter, deflagratingcharge, shear disc, fuse, grommet, and wires.

From the above description of a preferred embodiment of the invention itwill be noted that there is provided a simple detonator for a detonablefuse, comprising only means which are quite insensitive to ordinaryhandling shock; the detonator and associated apparatus being easily andquickly assemblable without danger of accidental detonation orexplosion, and the apparatus being readily disassemblable after usagewhereby the expendable parts .may be easily and quickly replaced. Theinvention thus permits safe and rapid assembly of well casingperforators and like equipment by relatively inexperienced or unskilledworkmen, and in the field, accordingly, greatly reducing the cost anddanger of such work and the time required for equipment servicing.

It is apparent to those skilled in the art to which the inventionpertains that many modifications of the apparatus and its components mayreadily be effected; hence to be limited to the specific details of thedescribed preferred embodiment of the invention is not desired, but whatis claimed is:

l. A readily and safely renewable detonator for a detonable fusecomprising: readily demountable cylindrical upper and lower supportmembers in substantially axial alignment; an axially bored and chamberedplug snugly mounted in the upper end of said lower support member; adeflagrating charge and an igniter therefor slidably insertable into thechamber of said plug; a disruptable element closing said chamber; abored member removably secured in the bore of said plug, with the borethereof covered at one end by said disruptable element; and readilyassembled means for holding said plug in said supports and serving tohold and position an end of a detonable fuse insensitive to ordinaryhandling shock in substantially axial alignment with said bore; wherebyupon ignition of said charge by said igniter said disruptable element isdisrupted and at least a portion thereof propelled along said bore andinto detonating impingement with said end of said fuse, and whereby thefuse is detonated without any material sensitive to ordinary handlingshock. 4 2. A readily and safely renewable detonator for a ,detonablefuse comprising: readily demountable cylindri- ;cal upper and lowersupport members in substantially axial alignment; an axially bored andchambered plug position an end of a detonable fuse insensitive toordinary handling shock in substantially axial alignment with said bore;whereby upon ignition of said charge by said igniter said disruptableelement is disrupted and at least a portion thereof propelled along saidbore and into detonating impingement with said end of said fuse, andwhereby the fuse is detonated without any material sensitive to ordinaryhandling shock.

3. In a well casing perforating apparatus in which a series of detonablecharges of material insensitive to ordinary handling shock are arrangedto be detonated in rapid succession by a detonable cord fuse likewiseinsensitive to ordinary handling shock and extending to said detonablecharges, a detonator arranged to detonate said fuse and comprising:readily demountable cylindrical upper and lower housing members for saidcharges, in substantially axial alignment, said housing membersproviding respectively upper and lower support members; an axially boredand chambered plug snugly mounted in the upper end of said lower supportmember; a deflagrating charge and an igniter therefor slidablyinsertable into the chamber of said plug; a disruptable element closingsaid chamber; a bored member removably secured in the bore of said plug,with the bore thereof covered at one end by said disruptable element;and readily assembled means for holding said plug in said supports andserving to hold and position an end of a detonable fuse insensitive toordinary handling shock in substantially axial alignment with said bore;whereby upon ignition of said charge by said igniter said disruptableelement is disrupted and at least a portion thereof propelled along saidbore and into detonating impingement with said end of said fuse, andwhereby the fuse is detonated without any material sensitive to ordinaryhandling shock. '4. In well perforating apparatus including a sealedcarrier providing an elongated hollow spaced therein, shaped chargeperforating units mounted in the hollow space of said carrier andadapted to fire outwardly through the walls of said carrier, and adetonable cord fuse insensitive to ordinary handlingshock extending indetonating relation to said shaped charge perforating units, thecombination therewith of adetonator for said fuse comprising: an axiallybored and chambered plug readily removably mounted in the hollow spaceof said carrier; a deflagrating charge and an igniter therefor slidablyinsertable into the chamber of said plug; a disruptable element closingsaid chamber; a bored member removably secured in the bore of said plug,withthe bore thereof covered at one end by said disruptable element;readily assembled means for holding said plug in the hollow space ofsaid carrier and serving to hold andposition an end of said fuse insubstantially axial alignment with the bore of said bored member;whereby upon iginition of said charge by said igniter said disruptableelement is disrupted and at least 10 a portion thereof propelled alongsaid bore and into detonating impingement with said end of said fuse,and whereby the fuse is detonated without any material sensitive toordinary handling shock.

References Cited in the file of this patent UNITED STATES PATENTS120,963 Gomez Nov. 14, 1871 839,194 Du Pont Dec. 25, 1906 1,322,083Barlow Nov. 18, 1919 2,265,982 Bolton Dec. 16, 1941 2,604,044 SevoldJuly 22, 1952 2,617,326 Morris Nov. 11, 1952 2,627,160 MacDonald Feb. 3,1953 2,629,325 Sweetman Feb. 24, 1953 2,649,736 Phillips Aug. 25, 19532,662,474 Turechek et a1 Dec. 15, 1953 2,705,920 Kanady Apr, 12, 1955

